Lisle Corporation released an inline spark tester with coil-on-plug wire to visually check spark energy.
To use the tool, technicians connect the tool between the spark plug and the plug wire. The short wire is double ended to offer both a straight boot and a 90-degree boot. While the engine is running, the tool will flash a mirror image of the ignition spark.
An additional 7-in. extension plug wire is included to use on hard to reach coil-on-plugs.
For more info: lislecorp.com